Effects of Fire on Bark Beetle Presence on Jeffrey Pine in the Lake Tahoe Basin

An investigation into the effects of low intensity, late-season prescription fire on Jeffrey pine (Pinus jeffreyi Grev. & Balf.) and associated short-term presence of various bark beetles of the family Scolytidae was completed on forests along the north edge of Lake Tahoe, Nevada. A total of 38 permanent 0.040-ha plots were located among five different prescription burn sites treated during October 1997. An additional twenty-seven 0.040 ha plots were located in adjacent unburned forest stands. All trees within-study plots were visited thrice between June and October of 1998. Results showed a highly significant correlation between burning and bark beetle presence. Over 24% of trees in prescription burn plots were attacked by one or more species of bark beetle. Less than 1% of all non-burned trees were similarly attacked. Highly significant multiple logistic regression models were developed for each of the two occurring species of Dendroctonus and a composite model for all observed species of Ips. The indirect burn severity measurements of crown scorch, duff consumption, and bole scorch were highly significant; other tested variables were species specific or not significant